.. The 38 foot boat that the designers want people to buy instead of a heavy 32 footer will not have the same motion comfort.
Motion comfort has to do also with LWL. A bigger boat has a more comfortable wave passage. Regarding the type of motion of an heavy boat versus a light one, well it is debatable, some like the big slow pitching of the old boats, some prefer the faster but less ample movements of a modern boat.
It is for each one to chose its preference.
This is only one example of a hundred: On a delivery return from Hawaii on a very modern 46 foot high performance, racer/cruiser, We were pounding so horribly that we had to slow the boat way down and move much farther off course.
Of course, in what concerns going upwind a fast boat is always more uncomfortable than a slow boat. If you cannot take the pounding that power and speed can induce, or just don't want to, you have just to go slower and it seems it was what you have done. A fast boat can go slower, a slower boat cannot go faster
Concerning the smaller sizes of long distance voyaging boats, the modern designs are falling way short of of their promise. ...
At this point in this post I offer one more disagreement with your comments. SPEED I must ask you, how much faster is that modern 38 footer going to be going than the heavy 32 footer that the designers want us to buy? (don’t forget to store the dinghy on that 38 footer) In my opinion, and I have sailed both, the real world answer is, very little, IF at all.
You can only be kiding
Between a westsail 32 and a good light cruiser like a Salona 38? Maybe 4 days in an Atlantic crossing? Maybe more if the Westsail has bad luck and the wind is weak. On coastal cruising without trade winds the difference will be a lot bigger.